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Case Presentation:
GIST
9th Annual Clinical Cancer Update Conference
Squaw Creek, North Lake Tahoe
January 2010
Anne Espinoza, M.D.
Hematology/Oncology Fellow
University of California, San Francisco
Initial Presentation
• 73 y/o previously healthy F with 3 month
history of abdominal pain radiating to left
shoulder
• associated symptoms: early satiety, bloating
• eating well, no weight loss, denies n/v
• no evidence of GI bleed
• Patient evaluated by her PMD:
• labs, abdomen/pelvis CT ordered
Initial Work-Up
• Labs – normal CBC, Cr, LFTs
• Abdominal/Pelvis CT
• 16.4 x 9.2 cm mass in LUQ located on
anterolateral surface of gastric body
• central necrosis
• no evidence of metastatic disease
Abdomen/Pelvis CT
CT-guided biopsy• moderately cellular proliferation
of fusiform spindle cells in whorls and short intersecting fascicles
• estimated mitotic activity• 10mf/50hpf
• immunohistochemical stains• CD 117 POSITIVE
• CD 34 POSITIVE
• negative:• S-100, muscle specific actin,
desmin, keratin, EMA, mucin
DIAGNOSIS: GASTROINTESTINAL STROMAL TUMOR (GIST)
Additional Work-Up
• Endoscopic Ultrasound
• 18 x 8 cm gastric mass, subepithelial
• arising from proximal inferior stomach
• location: 4cm distal to GE jxn with direct
invasion of stomach over 12 x 7 cm area
• no evidence of associated lymphadenopathy
Additional Work-Up
• PET/CT
• LUQ mass markedly
FDG-avid (SUV 14.7)
• hypermetabolic lesion
in liver not seen on
previous CT scan
QUESTION #1
• What would you recommend as the first
step in management?
1. surgical resection
2. neoadjuvant imatinib with plan for future
resection
3. imatinib with no plans for resection
Initial Treatment
• Decision made to start cytoreductive
treatment with imatinib given the extent of
operation that would be necessary.
QUESTION #2
• Would you perform a mutational analysis
prior to starting imatinib?
1. YES
2. NO
Initial Treatment
• Patient started on imatinib 400 mg daily
• After initiation of imatinib, patient
developed significant skin toxicity (diffuse
macular papular rash)
• imatinib held briefly, then dose reduced to 200
mg daily
• skin toxicity resolved
• follow-up imaging showed no response to
treatment
QUESTION #3
• What would you do now, given lack of
response with low-dose imatinib?
1. no further therapy
2. increase imatinib back to 400 mg daily
3. change to sunitinib
4. start chemotherapy
5. proceed to surgical resection
Continued Therapy
• Imatinib increased back to 400 mg daily
• no recurrent skin toxicity
• Follow-up PET/CT scan showed
significant response to therapy:
• decreased size of primary and liver lesion
• decreased metabolic activity of both lesions
Imaging: baseline & post-imatinib
BASELINE CT CT post-imatinib
Imaging: baseline & post-imatinib
BASELINE PET/CT PET/CT post-imatinib
Continued Therapy
• Patient continued on imatinib at 400 mg
daily for approximately six months
• At six months, imaging showed plateau in
response
QUESTION #4
• What would you do now that patient has had a plateau in response?
1. continue current dose imatinib
2. increase imatinib to 800 mg daily
3. change to sunitinib
4. attempt surgical resection of primary lesion with hepatic metastasectomy or RFA to liver lesion
Surgical Resection
• Patient taken to OR I she underwent:
• subtotal gastrectomy
• partial hepatectomy
Pathologic Findings
15.5 x 5.9 x 6.9 cm mass arising from gastric
wall with internal cystic degeneration
Pathologic Findings
specimens from liver resection showing significant necrosis
(imatinib treatment effect)
20X 200X
Pathologic Findings
area of viable GIST CD 117 stain
QUESTION #5
• What would your plan be for post-
resection treatment/surveillance?
1. surveillance imaging (PET/CT or CT), no
further therapy unless recurrent disease
2. adjuvant imatinib therapy
QUESTION #6
• How long of a treatment course with
adjuvant imatinib would you recommend?
1. six months
2. one year
3. two years
4. indefinite therapy
THANK YOU!